In a stream near the gates of Florence the PAN troupe bumped into a being that seemed to have fallen from another planet. With the elegance of a medieval warrior the Potamon Edule, this alien, has a long tale to tell. It arrived from the sea after many vicissitudes, it adapted itself to the fresh water streams. Very little is known about this crab and it runs the risk of disappearing from the face of the earth before more can be found out about it.